It is well established in the surgical field to use RF energy to perform therapeutic activities such as coagulate, dessicate, cut, cauterize, or dissect tissue. Accordingly, the use of RF energy is common in various types of surgical instruments. Additionally, it is common practice to use RF electrosurgical instruments that are either monopolar or bipolar.
Generally, in monopolar RF electrosurgical instruments, a single pole, such as an electrode, is located on the instrument for transmitting RF energy from a power source through the patient to a second pole, normally a grounding pad, which is located at an exterior portion of the patient's body. Since the grounding pad is connected to the power source, this energy transmission results in a complete electrical circuit. Only that tissue at or immediately near the instrument electrode receives the RF energy for performing one of the therapeutic actions outlined above.
In bipolar RF electrosurgical instruments, first and second poles, normally two electrodes, are located in close proximity to each other such that RF energy is transmitted from a power source to the first electrode through tissue to the second electrode, and returned through a conductive return path in the instrument. Bipolar RF instruments provide a complete circuit when activated and only that tissue located between the two poles is substantially effected by the therapy. Collateral tissue effects are experienced at adjacent tissue immediately located at each pole.
Some widely known examples of monopolar and bipolar RF electrosurgical instruments are outlined below. For example, U.S. Pat. No. 4,625,723 to Altnether et al., describes an electrosurgical monopolar RF pencil having a relatively flat spatula blade for cutting and coagulating tissue.
Another type of RF electrosurgical instrument is a pair of bipolar electrosurgical scissors such as those described in U.S. Pat. No. 5,352,222 to Rydell. Each scissor blade is a distinct pole or electrode for effecting coagulation and cutting of tissue between the blades. It is also common for electrosurgical scissors to be used as a monopolar device in conjunction with a grounding pad.
U.S. Pat. No. 4,418,692 to Guay describes electrosurgical forceps for use as a tubal cauterization and ligation device. This device can be used as either a monopolar or a bipolar device. Upon activation of a button, the jaws or electrodes of the forceps are closed around a structure, such as a fallopian tube, by releasing compression of a spring causing contact arms of a piston to contact conductive pads for completing the electrical circuit. This particular design is used as a safety feature to prevent electrification of the electrodes when they are in the open position.
U.S. Pat. No. 2,031,682 to Wappler et al. discloses electrosurgical forceps that can be either monopolar or bipolar. The device includes one fixed jaw and one pivotal jaw with an electrified cutting wire. Both jaws are open loop configurations which permit the cutting wire to travel into the open portions for coagulating and cutting tissue contained between the jaws.
U.S. Pat. No. 5,674,220 to Fox et al. describes a bipolar forceps device that also utilizes two jaws having an open loop configuration. A mechanical cutting blade is advanced into the open area to cut the coagulated tissue after the jaws have been energized and the tissue has been coagulated to the surgeon's satisfaction.
Another type of electrosurgical device is shown in U.S. Pat. No. 4,043,342 to Morrison, Jr. The device utilizes an active cutting electrode, such as a needle, which is spring biased such that the needle is forced deeper into the tissue or incision as the electrical cutting proceeds.
Presently, there is no known electrosurgical instrument that is pressure activated by a force exerted at the distal end of the instrument upon application to tissue or material.